How can he get his former boss to pay him the wages he previously earned?

My boyfriend recently quit his last job because his boss had not paid him for three weeks and he refused to continue to work if he wasn't getting any money for it. He has sent his old boss an email a day for the past week reminding him to pay him, but his boss totally ignores any email or call he receives. He works based on a contract they had established, and he would send his old boss weekly invoices which the boss was entitled to pay. My boyfriend has a copy of the contract and every invoice he's sent, but he doesn't know how to get him to pay him for the last 3 weeks he had worked. The total amount he needs to be paid is $300, but as far as small claims court goes that's not going to even be worth it in the end. How can he get his boss to pay him the money he earned without spending all of it on a lawyer to get it from him?